The use of security cards is now wide-spreading, accompanying an increase of types of the security cards. The security cards now in use includes, for example, ID cards, card keys, cash cards, bank deposit cards, membership cards, credit cards, pre-paid cards, telephone cards and so on. Those security cards generally make use of a data storage medium in the form of an IC chip, a length of magnetic recording tape or the like. As compared with cashes or any other valuable personal possession, the security card is relatively safe and convenient for a person to carry and use, however, the recent social problem is an increase of forgery and/or unauthorized use of the security cards.
To prevent the security card from being forged, various approaches have been employed. Most of the approaches include visual verification of the security card with naked eyes and electronic or magnetic verification of security data electronically or magnetically recorded on the security card. For the visual verification, the security card has visually readable data affixed to or printed on one surface thereof. The visually readable data includes a uniquely imaged hologram, a unique rainbow pattern, a micro-printed indicium, metamerism-based hidden characters and an opal-coloring.
On the other hand, for the electronic or magnetic verification, the security card a security data storage medium permanently affixed thereto, embedded therein, or printed thereon, and the security data stored in the storage medium and unique to the particular security card can be read and verified by the use of a corresponding electronic or magnetic reader apparatus. Examples of the security data storage medium include a pattern of punched hole, a length of magnetic recording tape or coating, a magnetic bar code, an azimuth recording, and a group of magnetic stripes.
While the various approaches to prevent the security card from being forged have been implemented, forgery experts are getting dexterous. One of the reasons therefor appears to be that they are good at analyzing the card reader to steal the structural details of the security card so that the security card can be forged based on the analyzed structural details.
With the advent of the age of wide-spreading cards, demands have been made for the security cards and the associated card reader that can hardly be forged or copied and that are less costly while securing a high level security.